No aero drag when the wheel is under vacuum. Have to imagine the bearing system is built to handle it though.

 

They were also subject to being oversped in that configuration. I would love to revisit it with a modern ECU and a DBW throttle. I think if you coupled all of that with a turbo speed sensor that it would be easy to maintain a safe max shaft speed in vacuum.

 

it would require some intersting control strategies as it would not be following the main throttle directly.. Interesting stuff.

 

Yeah, modern control hardware could probably make it happen pretty easily.

I was more talking about thrust loads when putting the compressor in vacuum though. Ball bearing turbos use angular contact bearings and I don't THINK they would be too happy with thrust loads in the opposite direction then what they normally see. I could see them smoking like crazy too.

There are some pretty cool turbo F1 and GrpB documentaries though on YouTube that actually give a great look at the era. I'd say what is being done today on the street car side is actually pretty inline with what was top tier technology of that era. Lots of the parts that you see in those documentaries could damn well be mistaken for stuff being used today.

 

That would be no different from running a carburettor in front of the turbo. When you size it right you don't need a wastegate at all.
As was done regularly 35 to 40 years ago with v8s.

 

Not exactly, there was a pre and post turbo TB on those old F1 cars.

 

As far as vacuum goes, with a carb, the inlet is always in vacuum.